Telephone teansmittee



L t e e8 h S v lm e e h Sv 2 um E m1 .n GS EN ...1M RT OE NN EP E Tn.-YE T d d o M o N No. 508,829. Patented Nov.14,v1898.

w/r/VESSES t m A fr0/swf Ys 'rhs NATIONAL LITHUGHAPHINQ coMPANv.

(No Model.) 2 Sheets-Sheet 2.

B. NORIBGA. TELEPHONE TRANSMITTER.

No. 508,829. vPatented Nov. 14, 189s.

ATTORNEYS me NATloNAL L ooooooooooooooooo Y.

I -UNITED STATES -PATENT OFFICE.

ELOY NORIEGA, OF MEXICO, MEXICO.

TELEPHONE-'TRANSMITTER sPEcIFIcATIoN forming pea ef Lettere Patent No.508,829, aerea November 14,1893.

Application iled February 4, 1891. Serial No. 380.172. (No model.)

`.To a/ZZ whom i# may concern:

Be it known that I, ELOY NORIEGA, of Mexico city, Mexico, have inventeda new and Improved Microphonic Telephone-Transmitter, of which thefollowing is a specification, reference being had to the annexeddrawings, forming a part thereof, in which- Figure lis a sideelevation,partly in section, ofmy improved microphonic telephonetransmitter. Fig. 2 is a vertical transverse section of the same. Fig. 3is a rear elevation o f a modified form. Fig. 4 isavertical transversesection; and Fig. 5 is a front elevation of a complete telephone,including the receiving and transmitting instruments, induction coil andsignaling mechanism, also showing a modified form of the transmitter. g

Similar letters of reference indicate corresponding parts in all theviews.

The object ofmy invention is to provide a microphonic Vtelephonetransmitter, capable of utilizing a heavy current, and of producing thevariations of Vcurrent necessary for the transmissiony `of speech overlong distances; also to provide atransmitter which willremain inadjustmentand work uniformly und'er all conditions.

My `invention consists in the combination with a diaphragm provided withan electrical conducting surface, a series of carbonvbars attached tothe diaphragm, and bearing upon the conductin g surface, and anadjustable bar provided with a chamberV containing elasticabsorbentmaterial held against the carbon bars, all las will behereinafter more fullydescribed. Y l

The annular frame A, is provided lat the top and, bottom with arms B,B', and with aperturesafor receiving the screws by which the frame isfastened tothe telephone box.

' .Upon diametrically opposite sides of the annular frame are securedspring clips b, which extend inwardly over theV diaphragm C, and hold itin place inthe frame A. The edge of the diaphragmisinclosed in a softrubber band c, which modifies the vibrations of the diaphragm andprevents any electrical connection betweenthe diaphragm and the frame A.

Upon the rear face of the diaphragm C is secured a thin plate ofconducting material,

and to the diaphragm are bolted two` carbon bars D, D', in which aremade transverse holes for receiving the ends of the carbon rods d,

which fit the holes loosely and rest normally upon the thin plate ofconductingmat-erial attached to the diaphragm. The carbon bar D isprovided with/a conductor e, and the carbon bar D', in a similar way, isprovided with a conductor e'.

To the arm B, is attached a spring f, which extends toward the arm B',and parallel with the diaphragm C. To the springfis secured a bar E,which is provided at its upper end with a lug g, and is angled at itslower end to adapt it for engagement with the adjusting screw F. To thelug gis attached aspring h, which extends downwardly parallel with thediaphragm C, and carries a chambered bar G, in which is placed a bodyz', of bropus, absorbent material Which rests upon the carthe thincarbon plate'dti, attached to the diaphragm. The pressure of theabsorbent material i upon the carbon rods is regulated by turning thescrew F,fin one direction or the other, whichby engagingthe angled endof the bar E, causes it to move inwardly o r outwardly as required. y

The frame A is secured to the telephone box cover Z,whicheis providedwith a mouthpiece I, located opposite the center of the diaphragm C. Thediaphragm C is preferably made of wood, spruce having been found ,by

experiment to be the best wood for 'thepurpose. AThe diaphragm isprotected against the effects of moisture of the breath or theatmosphere, by a coating of Water-proof varnish, such as shellac.

In the modifications shown in Figs. 3 and 4, the diaphragm C is clampedin a cell A', by the mouth-piece I', which screws upon the cell. To thediaphragm C are attached the carbon bars D, D', as in the other case,and the carbon rods d, which are like those already described, arepressed against the diaphragm by fibrous absorbent materialpreferablyabsorbent cotton contained in a case G', carried by a spring h securedto the Wall of the cell A', and the adjustment of the spring h iseffected by the screw F' passing through-the back of the cell A'. Thecell A' 4bon rods d, and presses them lightly against IOO may be made ofmetal or insulating material such as hard rubber, but in any case theback 7' of the cell must be iliade of insulating material. The bindingposts e2, e3, attached to the back j, are connected electrically byliexible wires with the bars D, D. The back of the cell A in this lcaseis threaded externally to permit of screwing it into the door of thecasing of the telephonie apparatus.

In the form of transmitter shown in Fig. 5, the construction is the sameVas that shown in Figs; l and 2, with the exception of the omission ofthe bar E, the spring h, and the body t' of absorbent material, and theends of the rods d, which are made conical and inserted in conicalcavities in the carbon bars D, D. The casing J, which contains all theworking parts of the telephone, with the exception of the receiver,consists of a body 7e `and a cover Z, 4the two parts being connected bythe hinges m, m', m2, m3. To the inside o f the cover l is secured theannular frame A, and in the cover is placed the induction coilK.

In the body of the box is arranged a magneto-electric machine L of theusual description, also a magneto call bell M, of the kind commonly usedin connection with telephones, 4and in .one side of the box case ispivoted a switchy lever N, which extends outwardly through the side ofthe box, and is bent upward to form a key for receiving the telephonereceiver O. .The inner end of the lever N is connected with one end ofaspiral spring n, the other end of which is attached to a stud o, and inthe path of the inner end of the le# ver N, is arranged a contact pointp, which istouched by the lever N, when the said lever is moved by thespring n after lifting the telephone receiver O from the outer end ofthe said lever. The body lo of the box is furnished with binding postsq, q', and the cover Z is furnished at the bottom with binding posts r,r', and at the top with binding posts s, s.

The poles of the battery P are connected with the binding posts r, 1".The binding post r is connected with one terminal of the primary wire ofthe coil K, the other terminal of the said primary wire being connectedwith the hinge m2, which is connected electrically with the stud o. Thebinding post r is connected with the wire e leading to the carbon barD', and the wire e attached f to the carbon bar D, is connected with thehinge m', and the hinge is connected electrically with the contact pointp, so that when the telephone receiver O is lifted from the lever N, thesaid lever is tilted by the spring n, so as to touch the contact pointp, thus closing the local circuit.

The line circuit is from the ground Q through the binding post q', hingem3, the secondary wire of the induction coil, binding post s', onebranch of the double cord R, to and through the telephone receiver O,back to the binding post s, thence through the hinge m to the bindingpost q, andl through the line S to the distant station.

The signaling circuit is from the ground Q through the binding post q',.the polarized bell M, the magneto L, the armature of the magneto to thestud o, through the spring n, lever N, contact point p', to the wireextending to the binding post q, thence over the line tothe distantstation.

When sounds are uttered in the mouth piece ofthe transmitter, thediaphragm is vibrated and the current in the primary circuit is varied.by the variable contact of the carbon rods d with vthe carbon liningofthe diaphragm and with the bars D, D', and electrical impulses aregenerated -in the secondary Wire of the coil, which aretransmitted tothe distant station, and act upon the telephone receiver to producesounds like those made in the mouth piece of the transmitter.

Although the thin coating of -carbon ,attached tothe diaphragm sho-rtcircuit-s the electrodes to some extent,still when'theelectrodes arevibrated bythe move-ments of the diaphragm, the contact of theelectrodes with the thin coating of carbon varies the resistance of thispart of the circuit, and thus adds materially to the efficiency of theinstrument. The carbons used in my microphone are made according to oneof the following formulae:

Formula No. 1.-Carbon (charcoal), fortysix per cent.; carbon (coke),forty-four per cent.; water saturated with boric acid at fty per cent.,ten per cent.

Formula No. 2.-(larcon (soft charcoal), forty-six per cent.; carbon(coke), thirty-three per cent.; Water saturated'with boric acid atforty-six per cent., eight per cent.; plumbago, thirteen per cent,

Formula, lVo. 3.-Carbon', sixty-three per cent.; graphite, twenty-twoper cent;.plutn hago, seven per cent.; water saturated with boric acidat fifty per cent., seven per cent.; tar, one per cent.

Formula No. 4.Garbon (charcoal), iifty per cent.; carbon (coke), fourpercent.; graphite, thirty-two per cent.; plumbago, six V'per cent.; tar,one percent.; water, five per cent.

Formula, No, 5.-Graphite, sixty-six per cent.; carbon, twenty-ve percent.; tar, one per cent.; water, eight per cent.

FormulaNo. 6.- Carbon, sixty-six percent.; graphite, thirty per cent.;water saturated with boric acid at fifty per cent., four per cent.

, Formula No. 7.-Carbon, seventy-four per cent.; graphite, nineteen percent.; water saturated with gum-lac and alcohol at fifty per cent.

Ido not limit myself to the formulae enn merated, nor to the quantitiesstated, for these can be varied as desired. Carbons made according to mymethod are suitable for all classes of microphones.

The carbons are prepared according to the formulae as follows: Pulverize'it until reduced to a very ne powder, and then pass it through a finesieve of silk or metal, so as to IOO IZO

eliminate anylumps which would be prejudicial in making the paste. Thepaste, which is produced by mixing the carbon with the., othersubstances and the Water, is submitted to a pressure which can be variedfrom seventy-eight to ninety atmospheres. The strips, bars orcylindrical carbons (for any form can be obtained) which are thusobtained, and which can be of'the desired size, are placed immediatelyin an oven of the proper form .y

The plate ofvcarbon atthe backof the diafA phragm slightly decreases theresistance of the circuit, but the principal objectot' this constructionis to be able to divide or subdivide the current between the plates andthe .barskof carbon,if desired. By this means three improvements in thesystem of carbon microphones are obtained. These are as follows: First,when the resistance of the microL phone -is excessive, the telephonemessages are confused, so that articulate sounds are scarcelyperceptible; this difficulty is increased With an increase of thedistance over which-conversation is carried on. With the carbon plateintroduced into the combination, a perfectly clear and distincttransmission is obtained over a .largely increased distance. Second, asthe lpressure of the carbon plate on-the diaphragm canbe increased moreor less and the pressure o f the cylinders against thelplate can bevaried, and the pressureof the absorbent material ony the cylinders canbe varied, amore uniform yaction may he secured, the resistancebeingdivided or subdivided as abovestated, throughout the variouscontacts andv bodiesof carbon, thus causing a part of the current topass through the plate,

and a part throughth'elcarbon bars.` Third, f

the absorbent porous material is inserted for .the purposeofcollectingall the moisture of the carbon electrodes. Itis well knownthat .carbon is quite hygromatic, andconsequently carbon electrodesabsorb Water easily' and with very slight changes of temperature. Wa-

.ter is prejudicial to the transmission of speech and to acleardelivery. The absorbentmasov terial removesthewater kfrom thecarbon and Having thus describiedmy invention,l

claim as new and desire to secure by Letters ,Patent- 1. -In amicrophonic telephone transmitter, the combination, with a diaphragm .ofnonnconducting material, of a thinconductinglin-A ing attached to thediaphragm, apertured carbon bars secured to the diaphragm, transverseAgreatlyimproves'thel action of the microphone. i

carbon rods having their ends inserted inthe apertured bars With theirsides-resting upon the metal lininguof the diaphragm, and means `forpressing thetransverse carbon rods'for- Ward against the conductinglining of the diaphragm, substantially as specied.

2. A carbon electrodev `for microphones, formed ot' charcoal, coke, anda -solution of boricacid, combined in about the proportions stated.

3. A carbon' electrode for microphones,

formed of charcoal, coke, graphite, andan aqueous solution of boricacid,combined in about the proportions stated.

1 Witnesses: PEDRO NORIEGA. LUIS SANTA MARINA.

ELOY NoRIEeA. Y

